Risk-evaluation of Hi-tech Enterprise in the Process of Approaching Global Market

In the high technology industry, small and medium sized technology enterprises (SMSTEs) play a pivotal role in advancing the whole industry. To achieve sustainable development, they need to extend their scope of business activities beyond a national view and exploit international market actively to meet international competitions that increase quickly in the form of allocating resources within the scope of the world. However, the SMSTEs are also facing risks associated with themselves during the process of exploiting international market owing to their own restrictions, so what they should do is to consider risk evaluations in exploiting the international market.     

生态足迹影响因子的定量分析

人口的膨胀和人类工业化进程的加剧，使得人类向自然界获取越来越多的资源，同时向环境源源不断的输入废弃物，已经严重超过了自然生态系统的供给能力和环境容量，生态环境日益恶化，水土流失、草场退化、植被消亡、生物多样性锐减、全球变暖等情况已经严重到难以遏制的地步，危及到人类自身的生存。在和平与发展成为世界两大主题的今天，人们越来越关注可持续发展的问题。在现有资料的基础上，利用主成分分析方法，定量地讨论了中国各省（区市）1999年生态足迹大小与其影响因子间的关系。结果表明，生态足迹的大小是各省（区市）的大中型企业个数、全社会固定生产投资等众多因子共同作用的结果，其中总人口和GDP是生态足迹大小的主要影响因子，其因子载荷量分别达到了0.940和0.913。值得一提的是非农业人口与生态足迹的相关系数超过了农业人口，这说明由于消费模式和生活水平等的差异，非农业人口对生态足迹的影响大于农业人口对生态足迹的影响。在此基础上建立了生态足迹影响因子的多元线性回归模型，以期为生态足迹在进行区域可持续发展评价的方法上提供新的思路。     

三峡库区中低产土壤重金属含量及其与小麦吸收的关系

三峡库区中低产土壤的Hg,As,Cr,Pb,Cu五个重金属含量（除渝北区外），均在国家土壤环境质量标准内，属自然背景值一级标准。Cd和Zn高于全国土壤中的平均含量和背景值含量，属二级标准。土壤的重金属含量与土壤母质类型，pH值，阳离子交换量，有机质，无定形铁和物理性粘粒有关，同时存在一定的地域分布。重庆近郊的土壤所有重金属含量相对较高。土壤重金属的可给态或有效性含量极低，锌和铜不是过量，而是不足。小麦籽粒中As,Cr,Pb,Zn,Cu含量低于国家食品对重金属限量标准和小麦籽粒背景值标准，Hg,Cd含量高于国家规定标准。籽粒中的Cu,Zn含量是小麦茎叶中的2.0-2.2倍，而茎叶中的Hg,Pb,As,Cr,Cd含量明显高于籽粒。     

滆湖水华初期浮游植物群落特征及与水环境因子相关性分析

为探究滆湖水华初期浮游植物群落特征及与水环境因子的相关性,于2018年5—7月在全湖布设22个点,调查研究滆湖水华初期浮游植物群落时空分布特征,并对引起水华主导环境因子进行分析.结果表明：①共获得7门119属,优势属为绿藻门的小球藻与球团藻、蓝藻门的鞘丝藻与微囊藻,其中湖心区域浮游植物丰度与多样性小,均匀性低,属于中偏重污染区域;湖北区以北属于中污染区域,蓝藻堆积严重;西部沿岸及南端区域属于中偏轻污染区域.②冗余分析得出,湖心藻类与水温（T）有强相关性,与叶绿素a（Chl-a）、溶解性总磷（DTP）、pH、溶解氧（DO）呈一定正相关性;湖北区以北藻类与底泥有机质（OM）、水体悬浮物（SS）、Chl-a及DTP呈强相关性,与T呈一定相关性.T与多项环境因子相关,均值从26.1℃上升到32.4℃;OM与有机磷（OP）呈高度相关性（p<0.05,r=0.892）.水华发生的主导环境因子为T、DTP与pH,底泥OM及OP有一定影响.     

有机废物厌氧发酵生物合成己酸研究进展

厌氧发酵处理有机废物并合成高价值羧酸盐的技术日趋成熟。尤其是己酸作为产物之一,因其附加值高,易于分离,用途广泛,越来越受到关注。微生物合成己酸需要电子供体及受体。详细介绍了乙醇、乙酸分别作为电子供体、受体合成己酸的机理——逆β氧化反应,总结合成己酸底物以及影响合成的因素（温度、pH值、水力停留时间、竞争路径、氢气分压、底物比例、氮源等）。目前采用科氏梭菌以乙醇为电子供体来合成己酸的技术较成熟,探索了利用乳酸为电子供体合成己酸的代谢机理,并指出开发乳酸转化合成己酸的技术可成为未来发展方向。     

Phosphate recovery with granular acid-activated neutralized red mud: Fixed-bed column performance and breakthrough curve modelling

Granular acid-activated neutralized red mud (AaN-RM) has been successfully prepared with good chemical stability and physical strength. However, its potential for industrial application remains unknown. Therefore, the performance of granular AaN-RM for phosphate recovery in a fixed-bed column was investigated. The results demonstrated that the phosphate adsorption performance of granular AaN-RM in a fixed-bed column was affected by various operational parameters, such as the bed depth, flow rate, initial solution pH and initial phosphate concentration. With the optimal empty-bed contact time (EBCT) of 24.27 min, the number of processed bed volumes and the phosphate adsorption capacity reached 496.95 and 84.80 mg/g, respectively. Then, the saturated fixed-bed column could be effectively regenerated with a 0.5 mol/L HCl solution. The desorption efficiency remained as high as 83.45% with a low weight loss of 3.57% in the fifth regeneration cycle. In addition, breakthrough curve modelling showed that a 5-9-1 feed-forward artificial neural network (ANN) could be effectively applied for the optimization of the fixed-bed adsorption system; the coefficient of determination (R²) and the root mean square error (RMSE) evaluated on the validation-testing data were 0.9987 and 0.0183, respectively. Therefore, granular AaN-RM fixed-bed adsorption exhibits promising potential for phosphate removal and recovery from polluted water.     

Long-term effects of silver nanoparticles on performance of phosphorus removal in a laboratory-scale vertical flow constructed wetland

Silver nanoparticles(AgNPs) have been widely used in many fields,which raised concerns about potential threats to biological sewage treatment systems.In this study,the phosphorus removal performance,enzymatic activity and microbial population dynamics in constructed wetlands(CWs) were evaluated under a long-term exposure to Ag NPs(0,50,and 200 μg/L) for 450 days.Results have shown that Ag NPs inhibited the phosphorus removal efficiency in a short-term exposure,whereas caused no obviously negative effects from a long-term perspective.Moreover,in the coexisting CW system of Ag NPs and phosphorus,competition exhibited in the initial exposure phase,however,cooperation between them was observed in later phase.Enzymatic activity of acid-phosphatase at the moderate temperature(10–20°C) was visibly higher than that at the high temperature(20–30℃) and CWs with Ag NPs addition had no appreciable differences compared with the control.High-throughput sequencing results indicated that the microbial richness,diversity and composition of CWs were distinctly affected with the extension of exposure time at different Ag NPs levels.However,the phosphorus removal performance of CWs did not decline with the decrease of polyphosphate accumulating organisms(PAOs),which also confirmed that adsorption precipitation was the main way of phosphorus removal in CWs.The study suggested that Ag NPs and phosphorus could be removed synergistically in the coexistence system.This work has some reference for evaluating the influences of Ag NPs on the phosphorus removal and the interrelation between them in CWs.     

Ozone pollution characteristics and sensitivity analysis using an observation-based model in Nanjing, Yangtze River Delta Region of China

Ground-level ozone (O₃) has become a critical pollutant impeding air quality improvement in Yangtze River Delta region of China. In this study, we present O₃ pollution characteristics based on one-year online measurements during 2016 at an urban site in Nanjing, Jiangsu Province. Then, the sensitivity of O₃ to its precursors during 2 O₃ pollution episodes in August was analyzed using a box model based on observation (OBM). The relative incremental reactivity (RIR) of hydrocarbons was larger than other precursors, suggesting that hydrocarbons played the dominant role in O₃ formation. The RIR values for NO_X ranged from –0.41%/% to 0.19%/%. The O₃ sensitivity was also analyzed based on relationship of simulated O₃ production rates with reductions of VOC and NO_X derived from scenario analyses. Simulation results illustrate that O₃ formation was between VOCs-limited and transition regime. Xylenes and light alkenes were found to be key species in O₃ formation according to RIR values, and their sources were determined using the Positive Matrix Factorization (PMF) model. Paints and solvent use was the largest contributor to xylenes (54%), while petrochemical industry was the most important source to propene (82%). Discussions on VOCs and NO_X reduction schemes suggest that the 5% O₃ control goal can be achieved by reducing VOCs by 20%. To obtain 10% O₃ control goal, VOCs need to be reduced by 30% with VOCs/NO_X larger than 3:1.     

Coupling mechanism of activated carbon mixed with dust for flue gas desulfurization and denitrification

To clarify the effect of coking dust, sintering dust and fly ash on the activity of activated carbon for various industrial flue gas desulfurization and denitrification, the coupling mechanism of the mixed activated carbon and dust was investigated to provide theoretical reference for the stable operation. The results show that coking dust had 34% desulfurization efficiency and 10% denitrification efficiency; correspondingly, sintering dust and fly ash had no obvious desulfurization and denitrification activities. For the mixture of activated carbon and dust, the coking dust reduced the desulfurization and denitrification efficiencies by blocking the pores of activated carbon, and its inhibiting effect on activated carbon was larger than its own desulfurization and denitrification activity. The sintering dust also reduced the desulfurization efficiency on the activated carbon while enhancing the denitrification efficiency. Fly ash blocked the pores of activated carbon and reduced its reaction activity. The reaction activity of coking dust mainly came from the surface functional groups, similar to that of activated carbon. The reaction activity of sintering dust mainly came from the oxidative property of Fe₂O₃, which oxidized NO to NO₂ and promoted the fast selectively catalytic reduction (SCR) of NO to form N₂. Sintering dust was activated by the joint action of activated carbon, and both had a coupling function. Sintering dust enhanced the adsorption and oxidation of NO, and activated carbon further promoted the reduction of NO_x by NH₃; thus, the denitrification efficiency increased by 5%-7% on the activated carbon.